These studies are devoted to immunobiology of human tumors. The experimental approach is twofold in nature, namely: 1) the identification and characterization of selected tumor-specific antigenic molecules which the tumor-bearing host may recognize and which may induce an immune response; 2) idenification of isolation and characterization of humoral and cellular immunoregulatory molecules of an antigen-independent nature which play a significant role in regulating the immune response of the host to tumors. This combined recognition, response and modulation of response appear to play a pivotal role in the biology of cancer.